1. Field of the Invention
The present invention relates to a camera, such as a bifocal camera having a telephotographic lens and a wide-angle photographic lens, wherein a light beam passed through the photographic lens is guided onto a film by means of an optical path changing member such as a reflecting mirror.
2. Description of the Related Art
There is provided, for example, a bifocal camera having within its body a telephotographic lens and a wide-angle photographic lens which are arranged in parallel to each other and can be selectively used for photographing, as a camera wherein a photographic light beam passed through the photographic lens is guided onto a film by means of a light-passage changing member such as a reflecting mirror. In general, this type of camera includes a stationary mirror provided on an optical axis of the telephotographic lens, an exposure opening positioned on an optical axis of the wide-angle photographic lens, and a movable mirror. The lenses are switched over from each other by moving the movable mirror between a telephotographic position wherein the movable mirror is situated on the optical axis of the wide-angle photographic lens and a wide-angle position wherein the movable mirror is retreated from the optical axis of the wide-angle photographic lens.
The camera having the above-mentioned structure, however, has the following problem: in the case where a rear cover of the camera body is opened to take out or insert a film while the movable mirror is situated in the telephotographic position, that is, the reflecting surface of the mirror faces the exposure opening, dust particles or the like may enter the camera body through the exposure opening and adhere to the reflecting surface of the movable mirror. In this case, good photographing cannot be performed.
According to a bifocal camera disclosed, for example, in U.S. Pat. No. 4,772,903, the movable mirror is shifted to the wide-angle position when the rear cover of the camera body is opened, whereby the reflecting surface of the movable mirror is protected against dust particles or the like.
The bifocal camera of the aforementioned U.S. Patent, however, has a problem mentioned below.
When a film is rewound while the movable mirror is situated in the telephotographic position, dust particles or the like adhered to the film enter the camera body through the exposure opening and adhere to the reflecting surface of the movable mirror. In addition, when the film is rewound, it slides on a film guide at high speed. Thus, emulsion coated over the film is peeled therefrom, and the peeled emulsion enters through the exposure opening and adheres to the reflecting surface of the movable mirror. As a result, good photographing is not carried out.
Moreover, an end portion of a film is normally curled inwards. Consequently, when the rewinding of the film is nearly completed, the end portion of the film may project into the camera body through the exposure opening as it passes over the exposure opening. In this situation, if the movable mirror is located in the telephotographic position, the reflecting surface of the mirror may be scarred by the end portion of the film projecting into the camera body. If the reflecting surface of the mirror is scarred, good photographing cannot be performed.